Photoacoustic study of surface plasmons in metals

A photoacoustic technique was used to observe the nonradiative decay of surface plasmons in evaporated thin films of silver. The signal amplitudes from an attenuated total reflection photon-plasmon coupler were measured as a function of the angle of incidence and the chopping frequency of p-polarized 1.96-eV photons. A 1-D analysis was made on the photoacoustic data in conjunction with simultaneously measured absorptance data. Such an analysis allowed us to separate the nonradiative and the roughness-assisted radiative relaxations of the plasmons and determine their relative probabilities.